Complex extrusion howto
There's a lot of different ways to do this. I suggest using modifiers for a non-destructive workflow. You can get the specific result you're looking for by using a few different modifiers, but perhaps the most straight forward is the Simple Deform Modifier.


Add the mesh for the propellor blade, with the origin centered along the Z-axis, and the mesh offset along the Y-axis. The origin position is key for the modifiers to work right.



2.Add an Empty, and rotate it accordingly (you will likely need to adjust the rotation after Step 3, depending on your configuration).


Add a Simple Deform modifier. This will be used for the bending of the mesh. Set the Origin field to use the Empty you created in step 2. Set the mode to Bend and adjust the Deform Angle as desired. 


Add another Simple Deform modifier. This second modifier will control the amount of twist. Set the modifier mode to Twist and once again adjust the Deform Angle as desired.